The present invention relates to a laser jaw setting system for CNC (computer numeric controlled) lathes.
One problem with lathes in general, including CNC lathes, is the difficulty in accurate placement of the workpiece holding jaws. Such placement still remains an art, dependent upon the skill of the lathe operator.
Even when the jaws are properly placed it is not always possible to leave the same set of work holding jaws on a lathe until the job is finished.
Setting the lathe chuck jaws in the proper work holding position is often done by using a pair of machinist calipers set at the diameter of the workpiece needed to be held by the jaws. These calipers are commonly held against the lathe chuck to give a visual reference of the specific workpiece diameter or inner bore needed to be held by the jaws. Alternatively, and if available, a piece of raw stock having the exact diameter of the workpiece is held against the chuck with one hand while bringing a chuck jaw down to the piece of stock and tightening it in the approximate location. This step is repeated for the additional jaws, typically a total of three. The process of holding the raw stock or calipers by hand concentric with the chuck to reference the jaw positions is very difficult, if not impossible, for the operator. The jaws must also be positioned in the unclamp position larger than the material to be held in order for the jaws to hold onto the material within the chucks clamping range. Holding the material in the center of the clamping range is important as to maximize the holding power of the chuck. There are other ways to set the jaws up that are specific to each operator but usually require two or three adjustments of all jaws in order to finalize their positions. This is time consuming and frustrating for the machine tool operator.
There have been many suggestions for devices to assist with the attachment of the work hold jaws thereto. Such devices have heretofor been too bulky, or require too many steps and excessive skill to use properly.
U.S. Pat. No. 6,931,971 describes a laser based jaw setting device for a CNC lathe. While this device is an improvement over many other suggested devices, it is only attached to the lathe for a short time and is then transported to another lathe for use thereon. Since the laser device is mounted to the front of the tool holding turret with a magnet and rod supplied by the operator, the tool position varies each time the operator positions the magnet on the front of the turret. The laser device is not part of the machine and it must be removed each time the machine tool is used since it would not stay secured to the turret and would interfere with machining processes if left on the machine. Each time the laser device is attached to a turret the laser beam must be calibrated to a known diameter as a reference point, which is time consuming and requires operator intervention.